This invention relates to a gas filter arrangement for ostomy bags, and to ostomy bags, particularly ileostomy bags, including gas filter arrangements.
There have been numerous prior proposals for gas filters for ostomy bags, of which the following patent specifications can be mentioned as a representative selection: U.K. No. 2,053,718; U.K. No. 2,122,090; U.K. No. 2,116,433; U.K. No. 2,031,282; U.K. No. 1,405,032; U.K. No. 1,550,960; U.K. No. 2,145,334; U.K. No. 2,149,306; U.K. No. 2,083,760; U.K. No. 1,379,464; U.S. Pat. Nos. 3,690,320; 3,865,109.
Particularly with ileostomy bags, one of the problems in bags having a filter is that the filter may become blocked due to the discharge being part-liquid, part-solid or of a slurry-like nature. Efforts have been made to design bags and pouches which meet the apparently conflicting requirements of preventing the discharge from reaching the filter and yet allowing gases within the bag to readily reach the filter. To the best of the applicant's knowledge and belief, there has been no satisfactory solution despite numerous efforts in the prior art, to the problem of allowing a wearer to make a quick and easy replacement of a filter which has become ineffective. Provision is made in various prior proposals for changing a used filter for a new filter. The constructions proposed are often complex, expensive to manufacture and awkward to manipulate. For example, U.K. Application No. 2 031 282 discloses a filter 6 placed over a vent hole in a bag. This filter would appear to be permanently attached to the bag, so, when its effectiveness reduces, a new bag would be required. U.K. Pat. No. 2,083,760 and U.S. Pat. No. 4,449,970 disclose a flatus filter which is folded over a top edge to cover perforations in each of two walls of a bag. With this arrangement one can remove an ineffective filter and replace it with a new filter but the manipulation necessary to peel or tear off the old filter and fold over and fit the new filter properly aligned with pinholes in the bag walls which are probably not easily visible is a difficult or impossible task for many users.